1. Field of the Invention
The invention relates to a vehicle steering column and, more particularly, to a collapsible vehicle steering column.
2. Brief Description of Prior Developments
U.S. Pat. No. 6,578,872 B2 discloses a steering column with pyrotechnic charges. The steering column has two telescoping members held at an extended position relative to each other by energy absorbing coil springs. The pyrotechnic charges can be actuated to selectively disengage the coil springs and provide a variable energy absorbing system. Other steering column designs using pyrotechnic charges are described in U.S. Pat. Nos. 6,749,222 B2 and 7,077,432 B2.
Steering column shear pins are also know which are set to fracture at a predetermined force when a driver impacts the steering wheel. Another conventional approach is to use a shock absorber in the steering column. However, this is expensive.